A Proteomic Approach Identifies Isoform-Specific and Nucleotide-Dependent RAS Interactions

Active mutations in the RAS genes are found in ∼30% of human cancers. Although thought to have overlapping functions, RAS isoforms show preferential activation in human tumors, which prompted us to employ a comparative and quantitative proteomics approach to generate isoform-specific and nucleotide-dependent interactomes of the four RAS isoforms, KRAS4A, KRAS4B, HRAS, and NRAS. Many isoform-specific interacting proteins were identified, including HRAS-specific CARM1 and CHK1 and KRAS-specific PIP4K2C and IPO7. Comparing the interactomes of WT and constitutively active G12D mutant of RAS isoforms, we identified several potential previously unknown effector proteins of RAS, one of which was recently reported while this article was in preparation, RADIL. These interacting proteins play important roles as knockdown or pharmacological inhibition leads to potent inhibition of cancer cells. The HRAS-specific interacting protein CARM1 plays a role in HRAS-induced senescence, with CARM1 knockdown or inhibition selectively increasing senescence in HRAS-transformed cells but not in KRAS4B-transformed cells. By revealing new isoform-specific and nucleotide-dependent RAS interactors, the study here provides insights to help understand the overlapping functions of the RAS isoforms. [Display omitted] •RAS interactome uncovers isoform-specific and nucleotide-dependent interactors.•Potential novel RAS effector proteins are introduced.•RAS interactors are possible new targets for RAS-driven cancer cells. Miller et al. presents a comprehensive and quantitative interactome of RAS, a protein found to be a driver of many human cancers. This resource identifies interactors of the active form of RAS (nucleotide-dependent) as well as isoform-specific (KRAS, HRAS, and NRAS) interactors of RAS. Several of the proteins identified were confirmed as being important for cancer cell viability or senescence. Exploring these proteins for further studies may lead to new strategies to treat cancers caused by RAS mutations.